TriQuint chip set allows CDMA tri-mode operation for handsets

HILLSBORO, Ore. -- TriQuint Semiconductor Inc. here released a four-chip set of CDMA receive-chain ICs designed to allow handset designers true tri-mode CDMA (IS-95 standard) operation, the company said today.

The devices, all operating with single 3-volt supplies, consist of two LNAs and two downconvert mixers (each in cellular or PCS frequencies). The chip set is designed with a high degree of operational flexibility and minimum additional circuitry, according to Cathy Arb, product manager at TriQuint's Wireless Division.

The TriQuint CDMA chips are packaged in small SOT23-8 packages, lowering their board space.

The chips can be implemented in a straightforward manner, with mode, gain select, and bypass switches monolithically integrated in the devices. This also minimizes receive function physical area on the phone circuit board.

Each LNA contains a CDMA mode with high and bypass gain settings. In addition, the TQ3131 and TQ5131 (operating in the 869- to 894-MHz range) have an AMPS mode, while the TQ3631 and TQ5631 (operating in the 1,930- to 1,990-MHz range) have a CDMA high gain/lowerlinearity mode.

The LNAs and downconverters incorporate on-chip switches that determine CDMA, AMPS, and bypass modes, thus eliminating the need for external switches and are controllable directly from the baseband circuitry. The supply current, input IP3, and gain is dependent upon the gain step and mode select which are externally accessible for performance customization. The Rx solution is far superior to the stringent IS-95 requirements.

Although specifically designed for the CDMA handset market, TriQuint said the new devices are appropriate for any application using the cellular or PCS frequency bands such as pagers, WLAN, or base station equipment.

The TQ3131 cellular and TQ3631 PCS LNAs are priced at 97 cents each in 1,000-piece quatities. The TQ5131 cellular and TQ5631 PCS D/C mixer are $1.09 each in the same quantity.